The present invention relates to a high-speed burst signal monitoring device associated with a burst signal processing apparatus in, for example, a time division multiple access (TDMA) communications system for monitoring receipt conditions of burst signals and transmitting a control message in response to a faulty signal from a burst transmit station or stations.
In a TDMA communications system, an example of communications systems which process burst signals, a multiplicity of stations share the same carrier frequency on a time division basis. Each of the participating stations sends burst signals intermittently to a communications line in synchronization with frame signals during those periods of time which are exclusively allocated thereto, so that the burst signals are multiplexed with those which are sent from the other stations without collision. In a TDMA communications system, therefore, a fault occurring in the time division control at any one of the participating stations is apt to immediately affect communications being held by all the stations in the system.
In light of this, a TDMA communications system needs to be provided with means for constantly monitoring receipt conditions of all the burst signals which are sent by the participating stations and, when a burst signal expected to be received at a predetermined position on the TDMA frame has not been detected at such position over a certain period of time, immediately instructing the receive station to send a control signal or a control message to a transmit station which is to transmit the burst signal, thereby controlling the burst of the transmit station. Usually, transmission of such a control message from a receive station to a transmit station is accomplished by use of a digital service channel or the like which is assigned as part of the data within a burst signal.
One approach to burst signal monitoring known in the communications art involves causing all the participating stations in a network to constantly monitor each other. Another known approach involves installing a master station in the network which controls all the participating stations and performs centralized monitoring of all the bursts of the stations. The problem with the prior art approach, whether it be the mutual monitoring type or the centralized monitoring type, is that the number of bursts to be received within one TDMA frame is considerable, particularly in a system of the kind covering a large number of stations, so that a monitoring device having a large capacity and operable at high speed is essential.
In a burst signal monitoring device employing any of the above-discussed approaches, an increase in the number of receive bursts is reflected by an increase in the number of circuit elements of the device, which in turn makes it difficult to realize a burst signal monitoring device capable of handling large capacity burst signals.
While the state of the art has been discussed concentrating to a TDMA communications system as an exemplary communications system and such system often includes an alarm signal as a control message, it should be born in mind that the content of the control message is not limited to an alarm function.